当前位置：首页 → 问答吧 → Bitblt导致无法用API绘图

Bitblt导致无法用API绘图

时间：2011-12-18

来源：互联网

去掉Bitblt那句代码，就能画出圆，加上却画不出。我已经用GetDC获得了窗体的场景，为什么复制场景后画不出图了，请问这是什么原因？
VB code


Option Explicit
Private Declare Function GetDC& Lib "user32" (ByVal hwnd As Long)
Private Declare Function Ellipse& Lib "gdi32" (ByVal hdc As Long, ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long)
Private Declare Function ReleaseDC& Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long)
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long

Private Sub Command1_Click()
    Dim PicDC As Long
    Form1.AutoRedraw = True
    'BitBlt hdc, 0, 0, 1000, 1000, Picture1.hdc, 0, 0, vbSrcCopy
    PicDC = GetDC(hwnd)        '获取设备场景句柄
    Ellipse PicDC, 0, 0, 100, 100         '画空心圆
    ReleaseDC hwnd, PicDC     '释放设备场景
End Sub